I fairly commonly find myself in a situation where I would like to display one label for certain features and another for other features in the same layer. QGIS doesn’t have an official way to split labels up into categories, and until now I’d resorted to having two layers to render otherwise identical features. But, in the new, excellent expression based labeling from Nathan Woodrow, I realized one can use an SQL CASE statement.

Over the last week I’ve started a new project, GTFSrDB, which allows you to connect GTFS-realtime with an SQL database, allowing app developers to use realtime data through SQL, just as easily as they use static data. Rather than worry about plumbing to connect GTFS and GTFS-realtime, they can focus on writing apps. It accomplishes two primary tasks: Keeping a database up-to-date with the latest realtime data, and Archiving historic real-time data.

When you load GTFS data into PostGIS using gtfsdb, you can’t access that data in QGIS because the tables don’t have a primary key in int4 format (the primary key is in text format). If your transit system uses numeric ids in text format, an easy fix is running this against each of your tables: ALTER TABLE stops ADD COLUMN gid int; UPDATE stops SET gid = stop_id::int; ALTER TABLE stops ALTER COLUMN gid SET NOT NULL; ALTER TABLE stops ADD CONSTRAINT stops_gid_uniq UNIQUE(gid); What this does is creates an integer ID field, populates it with the stop_id (or shape_id, &c.